Sacro Illiac Joint Pain SIJ Explained

Sacro Illiac Joint Pain SIJ Explained

What is the Sacro Illiac Joint Pain (SIJ)?

The SIJ is the joint between the lower segments of the spine, the sacrum, and the illium bone of the pelvis. The SIJ is given structural support by strong ligaments and muscular support gives the SIJ some degree of dynamic stability. Movements of the SIJ are subtle and can be confusing; however the main movements which occur at this joint are nutation and counter-nutation. Basically speaking, nutation refers to the top end of the sacrum tilting forward relative to the Illium and counter-nutation refers to the top end of the sacrum tilting backwards relative to the Illium.

What is Pelvic Instability?

Pelvic instability refers to uncontrolled counter-nutation of the SIJ. This puts direct stretch on the long dorsal ligament which is highly innervated with nerves and can cause pain often felt in the buttock and down the leg. The combined actions of several muscles are critical to achieve stability of the SIJ, including trasverse abdominus, multifidus, pelvic floor muscles, the gluteal muscles, latissimus dorsi, obliques and erector spinae. Weakness or poor neuromuscular recruitment of these muscles can cause sustained counter-nutation of the sacrum, increasing the risk of SIJ irritation.

Treating Pelvic Instability and SIJ Pain

Assessment to determine which muscles are deficient in stabilising the pelvis is critical for the treatment of SIJ pain. For acute SIJ pain, any exercise or movement which brings the sacrum into nutation should reduce pain. This includes SIJ mobilisations, stretching the hamstrings to inhibit them from pulling the sacrum into counter-nutation, taping across the SIJ or into nutation as well as traction in line of the SIJ to reduce stretch on the long dorsal ligament. Initially to achieve further pelvic stability, exercises to improve the strength and control of transverse abdominus are key. To then achieve dynamic control of the pelvis, strengthening the other muscles which stabilise the pelvis (Most commonly gluteus maximus and latissimus dorsi) is required.